Tehran, Iran (CNN) -- Eighty-six detainees, who were rounded up following last year's post-election violence in Iran, have been found guilty on charges of acts against the Islamic republic, Iran's semi-official Fars News Agency reported Tuesday.

According to the Iranian Judiciary, the verdicts were issued for charges such as "taking part in illegal gatherings, plotting against national security, propaganda against the Islamic Republic, membership in illegal and anti-revolution groups and disturbing public peace," Fars reported.

The Revolution and Public Court of Tehran said it sentenced most of the 86 defendants to prison terms. The court did not specify how long the sentences are for or when the defendants were arrested.

Opposition Web sites in Iran have reported that more than 4,000 opposition supporters have been arrested since June's disputed presidential election that returned hardline President Mahmoud Ahmadinejad to power for another term.

Iranian authorities blame the United States and Europe for influencing the protests and promoting violence in the country following Ahmadinejad's re-election.

CNN's Mitra Mobasherat and Shirzad Bozorgmehr contributed to this report.